Deck 1: Introduction

Question 1

In an electrochemical reaction, the change in Gibbs free energy ( $\Delta$ G) is related to the potential drop across the electrode-electrolyte interface

A) linearly
B) exponentially
C) logarithmically
D) none of the above

Answer 1

linearly

Question 2

As the potential is changed, the rate constant of a chemical reaction

A) changes linearly
B) changes quadratically
C) does not change at all
D) changes exponentially

Answer 2

D

Question 3

When the concentration of ions in solution is very low, (< 1 mM) Helmholtz model offers a better description of the double layer capacitor.

Answer 3

False

Question 4

For a capacitor with a certain capacitance (C), the relationship between current(i) and potential (E) in time (t) domain is given by

A) $$i = \frac { 1 } { C } \frac { dE } { d t }$$
B) $$i = C \frac { d E } { d t }$$
C) $$E = \frac { 1 } { C } \frac { d i } { d t }$$
D) $$E = C \frac { d i } { d t }$$

Question 5

If a metal, such as Cu, is used as a working electrode, and another piece of the same metal is used as a reference electrode, then any potential applied is evenly divided between the working and reference electrode.

Question 6

Given $$j = \sqrt { - 1 }$$
, if a sinusoidal potential of angular frequency ( $\omega$ ) is applied, then the impedance of an inductor with an inductance (L Henry) is given in complex notation as

A) $$\frac { 1 } { j \omega L }$$
B) $$\omega L$$
C) $$j \omega L$$
D) $$\frac { 1 } { \omega L }$$

Question 7

A three-electrode system is used in lab experiments so that

A) load is divided evenly between all electrodes
B) potential change across working electrode can be controlled
C) potential at the counter electrode is fixed
D) current at the working electrode is fixed

Question 8

The role of supporting electrolyte is to

A) support the electrochemical cell
B) increase the effective area of the working electrode
C) decrease reference electrode impedance
D) decrease solution resistance

Question 9

The impedance of an ideal inductor will have a phase of

A) 0 °
B) -90 °
C) +90 °
D) 180 °

Question 10

An inductor of inductance (L) and a capacitor of capacitance (c) are connected in series. The net impedance of this circuit is

A) $$j \omega L + \frac { j } { \omega C }$$
B) $$j \omega L - \frac { j } { \omega C }$$
C) $$j \omega C - \frac { 1 } { j \omega L }$$
D) $$j \omega C + \frac { 1 } { j \omega L }$$

Question 11

An ideal reference electrode is polarizable.

Question 12

Given $$j = \sqrt { - 1 }$$
, if a sinusoidal potential of angular frequency ( $\theta$ ) is applied, then the admittance of a capacitor with capacitance (C Farad) is given in complex notation as

A) $$\Gamma \frac { d \theta } { d t } = k _ { 1 } ( 1 - \theta ) - k _ { - 1 } \theta - k _ { 2 } \theta + k _ { - 2 } C _ { M _ { s a } ^ { 2 } }$$
B) $$\theta _ { ss } = \frac { k _ { 1 \dot { dc } } } { k _ { 1 \dot { dc} } + k _ { 2 } }$$
C) $$\theta _ { s s } = \frac { k _ { 1 dc } } { k _ { 1 \dot { dc } } + k _ { - 1 \dot { dc } } + k _ { 2 } + k _ { - 2 } }$$
D) $\theta_{ss}=\frac{k_{1 d c}+k_{-2} C_{M_{sol}^+2}}{k_{1 d c}+k_{-l d c}+k_{2}+k_{-2} C_{M_{sol}^{+2}}}$

Question 13

For an ideal reference electrode, the impedance should be very large.

Question 14

In the potentiodynamic polarization data of a simple electron transfer reaction (Fig. below), region (II) is

A) kinetic limited
B) mixed control region
C) diffusion-limited
D) adsorption limited.

Question 15

Consider an electrical circuit shown below.
For a given value of R₁, R_2, and C₂, the impedance at a wide range of frequencies can be calculated and plotted as a complex plane plot and Bode plots. If the capacitance C₂ is changed,

A) Shape of the complex plane plot will remain the same, but the points will move in the same curve
B) location of the peak in phase vs. frequency will change
C) both of the above
D) none of the above

Question 16

In chrono amperometry, ____________ is measured as a function of _____________

Question 17

Consider three resistors, R₁ = 150 $\Omega$ , R₂ = 200 $\Omega$ and R₃ = 250 $\Omega$ . When they are connected in series, the net impedance is (i)__________ $\Omega$ and when they are connected in parallel, the net impedance is (ii)___________ $\Omega$

Question 18

A resistor with resistance (R) is connected in parallel with an inductor with an inductance (L). The net impedance of the circuit is given by

A)
$$R + j \omega L$$ ,
B) $$R - j \omega L$$
C) $$\frac { 1 } { \frac { 1 } { R } + \frac { 1 } { j \omega L } }$$
D) $$\frac { 1 } { \frac { 1 } { R } - \frac { 1 } { j \omega L } }$$

Question 19

The impedance of an ideal capacitor will have a phase of

A) 0 °
B) -90 °
C) +90 °
D) 180 °

Question 20

Using the circuit given below, calculate the impedance at a frequency of 10^-5 Hz. Here, R_sol = 10 $\Omega$ , R_t = 100 $\Omega$ , C_dl = 10 $\mu$ F. Round the impedance values to one decimal. Z_Re = (i) __________ $\Omega$ and Z_Im = (ii) ___________ $\Omega$ .

Question 21

During the measurement of open circuit potential as a function of time, the counter electrode need not be connected.